Conventional snowmobiles typically have a skid frame assembly for supporting an endless flexible drive track. The skid frame assembly generally includes low-friction wearstrips respectively coupled to slide rails, a number of crossbrace axles extending from one slide rail to the other, a suspension system, one or more idler wheel assemblies, and other structural support. By way of example, a rear idler wheel assembly is coupled to an aft portion of the skid frame assembly and provides a surface on which the continuous track makes approximately a 160 degree turn. Because the rear idler wheel assembly is located sufficiently aft of the snowmobile's center of gravity it is desirable to reduce the weight of the rear idler wheels in order to more effectively centralize the overall mass for better handling. Therefore, the rear idler wheels are typically made of a lightweight, structural material and have spokes or lightening holes for weight reduction purposes.
A snowmobile rides on various non-uniform surfaces and all types of on- and off-trail conditions, as such it must be able to contend with many different riding environments. The terrain may change from smooth trails to large bumps and jumps to deep snow with occasional hidden rocks or stumps. Snow conditions can vary from grippy hard-pack to bottomless powder, from smooth trails to rough and bumpy ones. In turn, the idler wheel assemblies, and specifically the rear idler wheel assembly, should be optimized to strike a balance between weight and load capacity or structural robustness.